An ultrasound imaging apparatus obtains biological information by scanning a subject through an ultrasound probe. Moreover, the ultrasound imaging apparatus images the state within the subject based on the obtained biological information. That is, the ultrasound imaging apparatus sends a control signal regarding the scanning of the ultrasound waves to the ultrasound probe. Based on the control signal, ultrasound waves are sent to the subject through the ultrasound probe. In addition, the ultrasound probe receives reflected waves from the subject. Based on these reflected waves, the ultrasound imaging apparatus acquires biological information based on the state within the subject. Moreover, the ultrasound imaging apparatus creates an ultrasound image based on this biological information.
An ultrasound probe has, for example, the following configuration. The ultrasound probe comprises a piezoelectric transducer group with a 1-dimensional array or 2-dimensional array. On the side facing the radiation direction (acoustic radiation direction) of the ultrasound waves in said piezoelectric transducer group (hereinafter referred to as the “front face side”), an acoustic matching layer is placed with an electrode in between. The acoustic matching layer is placed for the purpose of matching the acoustic impedance of the piezoelectric transducer and the acoustic impedance of a biological object. On the side facing the direction opposite the radiation direction of the ultrasound waves in the piezoelectric transducer (hereinafter referred to as the “back face side”), a backing material is placed with an electrode and FPC (Flexible Printed Circuit) in between. Moreover, an intermediate layer with electric conductivity may be placed between the piezoelectric transducer and the backing material.
The ultrasound waves irradiated to the back face side of the piezoelectric transducer are attenuated and absorbed by the backing material. In addition, the structure of, for example, the piezoelectric transducer is supported by the backing material. The intermediate layer has higher acoustic impedance than the piezoelectric transducer, and is provided to enhance the radiation efficiency of the ultrasound waves. Due to the gap between the acoustic impedance of the intermediate layer and the acoustic impedance of the piezoelectric transducer, the ultrasound waves irradiated to the back face side of the piezoelectric transducer are reflected by these interfaces. Therefore, the ultrasound waves are sent out to the ultrasound wave radiation plane side that is the front face of the piezoelectric transducer. In addition, a wiring pattern (electrode lead) is provided on the piezoelectric transducer side of the FPC. Through the wiring pattern of the FPC, an electric signal is sent from the subsequent circuit to the piezoelectric transducer. Moreover, through the wiring pattern of the FPC, an electric signal is drawn from the piezoelectric transducer to the subsequent circuit.
As described above, the FPC is placed on the front face side in the backing material. This FPC is, for example, placed substantially parallel to the backing material so as to cover the front face side of the backing material. However, the FPC is folded toward the subsequent circuit side (the side opposite the piezoelectric transducer) at the end of the front face of the backing material, and extended toward the subsequent circuit side. If the FPC is not folded toward the subsequent circuit side at the end of the front face of the backing material, the FPC spreads in the array direction or lens direction in the ultrasound transducer. By preventing the FPC from spreading, the ultrasound probe is prevented from becoming larger. In addition, folding the FPC at the end of the front face of the backing material is also for the purpose of improving the impact resistance.
Moreover, the FPC and the construct (the piezoelectric transducer or the intermediate layer) are adhered to each other using an adhesive in order to improve the reliability of the connection. This construct may hereinafter be referred to as the “intermediate layer, etc.” For example, the side (the surface substantially parallel to the radiation direction of the ultrasound waves) of each intermediate layer, etc., in a 1D alignment or 2D alignment and the front face of the FPC are adhered (see, for example, Patent Document 1/FIG. 2, reference 140). That is, there is no adhesive layer on the plane in which each intermediate layer, etc., is facing the FPC. With such a configuration, the adhesive layer is provided in the position at which the intermediate layer, etc., on further end of the element alignment is adjacent to the front face of the FPC. That is, one interface to be bonded with the adhesive is the end of the side of the intermediate layer, etc., while the other interface is the face of the FPC facing the radiation direction of the ultrasound waves.
However, the above-mentioned FPC has a risk of breakage due to being folded. Consequently, there is a risk of breakage (such as disconnection) of the wiring pattern in the FPC. Moreover, in the process of manufacturing the ultrasound transducer, even when carrying out the procedure of firstly adhering the FPC and the intermediate layer (or the piezoelectric transducer) and then folding the FPC, there is a risk of breakage of the wiring pattern. That is, when trying to fold the FPC after the adhesive has set to some extent, the wiring pattern is folded in the state bonded to the adhesive that has been set. Consequently, a force may be applied to the wiring pattern in the direction of resistance to the bonded state by the adhesive to cause a breakage.
In order to prevent such a breakage of the wiring pattern at the folded section of the FPC, a coverlay (film, covering material) using, for example, a polyimide film may be provided on said folded section. This coverlay protects the wiring pattern.